Electrohydraulic moving device



Aug. 5, 1952 GREBE 2,605,613

u ELECTROHYDRAULIC MOVING DEVICE Filed Jan. 25, 1951 2 SHEETS-SHEET l Q /6 {Q 735 17 72 75 Y",

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\ (1) l8 En i I S 76 2 Pg f a; Q 33 33 Q W ML\\\\\\\\\\ Flfii l r; 29 "n". 2 38 Patented lg- 1 1 Y 7 Otto Grebe, OlpejGermany, assignor to-Elektro Mechanik G. 111. b. H., Wendenerhutte Uber Olpe, Germany Application January 23, 1951, Serial No. 207,311

In Germany January 30, 1950 (CLEO-52) Claims.

The present invention relates to an electrohydraulic moving device, and more particularly to an electrohydraulic moving device comprising electrically operated driving means, a pump driven by the same and displacing a pressure fluid such as oil, and a piston operatively connected to the pump so as to be actuated by the pressure fiuid displaced by the pump. 7

It is an object of the present invention to render theflpressure and/or the quantity of the fluid displaced by'th'e pump ea'sily controllable. It is another object of the presentinvention to keep the cylinder clearance of the pump as small as possible.

It is a further object of the present invention to simplify the design of the pump and to render the space required for the same as small as possible. w '7 It is still another object of the present invention to reduce jthe'joscillating masses of the membervcontrolling thepump. 7

It is anstill further object of the presentinvention to shield the piston and the part to be adjusted by thesame against vibrations of the p p e.

An electrohydraulic adjusting device according to the invention comprises in its broadest aspect a piston adapted to be connected to apart to be moved by the device, a pump operatively connected to the piston so as to displace the same by a pressure fluid displaced by the pump, a first 'electromagnet driving the pump, a first Winding forming part of the first electromagnet and energized byan alternating currentya control member inserted between the pump and the piston so as to control the flowv of pressure fluid from the pump to the piston, a secondelectromagnet driving the control .member, and a second winding formin part of the second electromagnet and energized by anjalternatingcurrent having the same frequency as the alternating current energizing thefirst winding.

Preferably thecurrent energizing the second winding has a phase lag amounting to fl5 compared to the current energizingthe first windmg. g In a preferred embodiment means areprovided for shifting the phase of the alternating current energizing the second winding'against the phase ofthe' alternating current energizing the first winding whereby the pressure'and quantity of th fluid displaced by the pump canrbe' adjusted. l i

Preferably means are provided forinverting the phase of' one of the currents energizing the windings in order to reverse the directions of the displacements of the pressure'fluid.

In a preferred embodiment'of'the' present invention the pumping system is tuned to the fre- 2. quency of the alternating current energizing the firstwinding. p

According to. a preferred embodiment of the present inventionthe control member istuned to resonance with the frequency of the alternating current s energizing the windings so that the control. slots'of thefcontrol member can be extended. e Y

Preferably the pump includes a piston and the control member is arranged at right angles thereto in order to keep as small as possible the cylinder clearance of the pump. w j

According toa preferred embodiment of the present invention "the control member is made hollow and resilient'means are arranged within the hollow control'member and render the same part of an oscillating system having a predetermined natural frequency. Thereb it is achieved that the design of the. pump issimplified and the'latter occupies very little space; at the same time the oscillatin mass of the control member is reduced. I

In a preferred embodiment of the present invention the first electromagnet driving the pump has ,a magnetic core carrying the first. winding,

the core and} thefirst winding being so' dimensiioned that the core is saturatedif a current at the rating voltage flows in the first winding. Preferably the second electromagnetdriving the control member has a magneticfcore carrying the second winding, the ore and the second winding being so dimefisioned'that the 'core is saturated if an alternating current at the rating voltage fiows in the second winding. I I

A' preferred embodiment of the present invention comprises in combination, a; tank containing a pressure fluid, a pump arranged within the tank and having a piston, a first electromagnet arranged in the tank and driving the pump, a first winding forming part of the first electromagnet and energized by an alternating current, a control member arranged in the tank, a cylinder arranged in the tank, a piston arranged in the cylinder and adapted to be connected to a part'to be moved by'the' device, the control member being inserted :between the pump and the cylinder so as to control theflow of pressure" fluid from duced by the pump and being independent of the I cylinder andthepiston' arranged in the cylinder.

Preferably, a" resilient hose connecting the pump and the cylinder serves as a chamber connects the pump and the cylinder and serves as a vibration-attenuating part of the securing means.

In another embodiment ofthepresent invention the cylinder is arrangedabove'the lid of .the tank and two corrugated tubes connected to the cylinder serve for suspending the pump and the electromagnets from the lid of the tank. Prefer ably the piston adapted for connection'with-the part to be moved is designed as a rotary piston.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The, invention itself, however, both as. to its construction and its method of-operajtion, together with additional objects.and, advantages,thereof, will be best understood from. the following descriptionof specific embodiments when read. in ,connection with the accompanying drawings, in which:

Fig. 1 is a side elevation, partly in section, of a first embodiment of the present invention;

Fig. 2 is a plan viewof. apart of Fig- 1 seen in the direction 2--2 Fig. 3 is a-side elevation, ,partly. in section, of the part indicated byithe line 3-3 of Fig- 1 and being at right angles to the same;

Fig. 4 is a wiring diagram showing the connections of the Windingsof .the electromagnets of the pump system toa single phase alternating current line;

Fig. 5 is a similar wiring diagramshowing the connection ofthe windings to a three-phase line; and

Fig. 6 is a sectional elevation of a second embodiment of the present invention.

Referring now .to'the drawingsr and first to .g Figures 1, 2 and 3,. a first electromagnet I0 drives a pump the piston I2 of whichis connected to the armature II of .the first electromagnet I0 and moves in a pump cyli nderl3. Thearmature II is underthe action of a plurality, e. g. four helical compressionsprings such as I4 which is shown in Fig. 1. The whole -ag regate, however, of four springs 14,14, -I4'-',.I4' can be seen from Fig. 3, eachspring abuttingagainst an extension I3 of the cylinder'I3. ,Thesprings I4 and I4 surround a rod II whichis rigid with th armature I I and ends in a member I I" abutting against theend of-the spring which does not abut against the extension I3. Similarly the springs I4" and 14" surrounda rod II"' which is rigid'with the; armature II ,and ends in a member-I I" against which the spring I4" abuts with-one endthereof. ;In this way it is accomplished that whenever the alternating .current supplied'to thewinding of the first electromagnet I6 passes through zero, the armature II is withdrawn fromthe electromagnet III by means of the springs I4, I4, I4, W, the latter being tensioned when the armature II is attracted by the electromagnet I0. When the armature II is withdrawn from the electromagnet II] the pump piston :IZ ejects'the oil which had been sucked in by thesame during the attraction of the armature II by the driving electromagnet II].

The pump cylinder 'I3- is .provided with a boring arranged at right angles to the piston I2 and accommodating a control member or slide I5 which is rigidly connected to the armatur II of secondelectromagnet I6. .10

a second electromagnet I6, also supplied with an alternating current as explained more in detail hereinafter. The control member I5 is preferably made hollow imiorder .to accommodate springs I8 and J9, rendering the armature I1 and the control member I5 parts of an oscillating system having twice the frequency of the alternating currents energizing the windings of the The springs I8 and I9 are separated from one another by a partition 20' of the control-member I5 against which each of the springs. -I8; and I9 abuts with one end thereof, the opposite ends of th springs I8 and IBfabutti'ng against stationary members I8 and I9; respectively. gdampening the oscillations of the control mem- The partition 26 serves for her I5 which, however, can also be dampened by the leaking pressurefluid such as oil.

The controlmember I5 -cooperates by means of control slots .I5- andlfi" withopenings 2I and 22 in the cylinderyl3tto lwhich hoses 33 and 33' are connected,lrespectively,..the arrows shown in full lines in Fig. l iishowin'g the direction of the oil flow if, for instance,. the current in the windings of the electromagnet I6.driving the control member I5'is leadingin phase as compared to the current. supplied .to the driving electromagnet III, the arrows ,shownindotted lines indicating the direction of the oil flow when the energizing current offthe vcontrol'magnet I6jlags v behind the current of the driving magnet I0.

Referring .now to Figs. 4 and 5, two embodiments of theconnection. of the windingsof the magnets I0 and I6 are shown. InFig. .4 the windings Ill and I6 are each connected to a single phase alternating currentline.. The winding In is directlyconnected tothe linewhereas the winding I6 is connectedto .theline by means of a double throw switch 16a whichconnectsin one position thereof one end of the winding I6 directly by means of a connection vI62) to one 'ter- 7 minal of the line whereas in the other position ofthe switch I60. acondenser IE0 is inserted between the one end of the winding I6 and the just mentioned terminal of .theline. It will be understood that .in .one position of the switch I6a thecurrent, in the winding I6 lags, and in the other position of the switch I6a leads, in phase with respect to thecurrent inthe winding I0.

In Fig. 5 the winding I6 isdirectly connected to two phases Bland SI of the three-phase line RST. The winding I6 is connected to the secondary 16a of arotary. transformer thestarconnected three-phase. primary I6d of which is -.connected-to,the phases RST. By adjusting the secondary IEe A of the rotary transformer any phase relation between the-currents flowing in the windings -I I) and I6 is obtained.

Assuming now that the current in the contro magnet I6 lags behindthe current in the driving magnet ID, the operation of thedevice so far described is as follows:

In the position shown in Fig. 1, the control member I5-is'in the middle or zero position and the pump-piston is-in its lowermost position.

' When thepiston I2 moves upward owing to an attraction-10f thegarmature- II by the electrocontrol member moves toward the lefthand side because the armature I1 is attracted by the elec-' I alternating current the phase positionof which can be arbitrarily adjusted for instance by connecting the winding l6 to the secondary We of a rotary transformer (Fig. the following effects are obtained:

(1) If the alternating current in the electromagnet I6 is in phase with the alternating current in the driving magnet [0, the piston l2 and the control member l5 carry out motions which are equally in phase with each other so that the quantity of fluid displaced by the pump is nil.

(2) If the alternating current in the control magnet [6 leads before the alternating current in the driving magnet I 0, the quantity of displaced fluid increases with increasing phase angle and reaches a maximum value at' an electrical phase lead of 45 since now thecontrol member 15 and the pump piston l2 carry out oscillations which are out of phase by 90. It should be noted that owing to the quadratic relation between the currents and the pulling force the frequency 'is doubled so that a phase difference of 45 of the; currents in the magnet windings is suflicient for obtaining a mechanical phase difference of 90 between the amplitudes of the pump piston I 2 and the control member [5.

(3) If, the alternating current in the control magnet l6 lags behind the alternating current of the driving magnetilll, the pump piston [2 will displace the fluid such as oil, however, in oppositedirection to that in the case (2). If the electrical phase diflerence is brought to 90 as compared to the maximum output of case (2) i. e. to 45, the pump displaces the oil with the maximum power in a direction opposite to that in which the oil is displaced in case (2).

In order to render the operation of the pump independent of variations of voltage it is advisable to design the core and the winding of the driving electromagnet so that the core is saturated at the rating voltage. In consequence thereof the magnetizing current changes according to the variations of voltage, but the flux generated by the magnetizing current in the air gap will be practically invariable within the range of voltage variations amounting to i%. It is equally advisable to design .the core and the windings of the control magnet I6 50 that the control mag net operates within the range of saturation so that the flux through the air gap and the magnetic force generating the same donot practically vary Within variations of the voltage amounting to:l0%.

Referringnow to Figs. 1 and 2, the piston 23 adapted to be connected to the part to be moved by the device is reciprocating within a pressure cylinder 24 which is arranged within an oil tank 25 enclosing also the magnetically driven pump system. The tank25 is filled to? the level 26 or thecylinder l3. *Theeyele'tsfl, snare integral with pressure fluid such as oil. A lid 21 closes the tank 25 at the upper side thereof and carries a terminal box 28 for the electrical connections to the windings of the magnets l0 and I6.

' The pump aggregate consisting of the driving magnet 10, the armature H thereof, the pump piston E2, the pump cylinder I3, the springs M, the control member IS, the control magnet. l6.

andthe armature l1 thereof is'suspended from the piston 23 is reciprocatedand moves the (not shown) connected to the "eye 36. 5

with the bridge member 13a; In-o'rderto prevent the transfer or vibrations to the-pressure cylinder 24 by the connection thereof with the pump system, the-latter is formed by resilient hoses 33, 33' whichfserve'a's vibration-attenuatrmgpartsel v,

The pressure cylinder 24""is arranged with the axis thereof parallel to th'e" axis'of' the pump piston I2 and is suspended fromthe lid 21. The suspension, however, 'need not be provided with vibration-attenuating means since the vibrations of the pump are sufficiently intercepted by the rubber metal blocks 3|, 32 and the hoses 33, 33'. The piston 23 is rigidly connected to piston rods 34, 35 protruding aboveand below, respectively, the cylinder 2 4 through g'asketssuch'as '35. The piston rod 34 carries at the upperend thereof an eye 36 serving for coupling the device to the part to be moved (not shown); v

The operation'of this device as 'follows:

When the'electrom'agnets'are energized as described more in 'detail hereinabove, the pump supplies oil in a controllableiquantity, as described hereinabove moremdetail, to the hoses 33, 33' and to the pressure'cylinder 24- so that part By lifting the lid-21-all essential elements of the device are rendered easily accessible and can be repaired in case of damage. I i

Referring now to Fig. 6,,thepump aggregate (not shown) is enclosed ina-container 39 which is connected by means of corrugated connecting members 37, 38 to thepressure,cylinder,42 containing a rotary piston 43. The, pressure cylinder 42 is arranged above -the ;=lid -4,I; of the-joil-tank 40 and the corrugated tubes31 :33-serve at the same time for suspending the container=39v and the pump aggregate arrangedtherein from. the lid 4|. The tubes 31, 3.8" are connected by openings 44, to the. pump aggregate within the container 39 and-through-openings-46, 41 to the pressure cylinder 42; .l

The operation of thisdevice is substantially the same asthat of the devicesshown in Figs. 1 to 3 except that the piston 43,is designed as a rotary' piston whichallows considerably to reduce the overall height of the device and to drive rotary devices such as flaps. l

It will be understood that each, of. he elements described'above, orutwo or more together, may also flnda useful application in other types .of electrohydraulic movingdevices differing from the types described above. 1 T

While I have illustrated and described the invention as embodied in an electrohydraulic moving device having an electrically operated pump, I do not intend to be limited .to the details shown, since various modifications and structural changes may be madewithoutdeparting in any way from the spirit of.-,I ny invention;

Without further-.vanalysis the. foregoing will constitute "essential characteristics'lof the generic v or specific aspects of thisj'inv'ention and,-'there- Letters- Platent is z fore, such adaptations should and are intended toibe; comprehendedz within the; meaning; and

rangeof equivalence. of the fo1lowing claims What lclaimaas new and desireato secure by 1; Anelectrohydrauliemoving;device; comprising: incombination; azpiston'gadapted toqbe connectedto apart5to bemoved by the devicegapump operatively connected; to :said', piston so as .todisplace the same by-apressure fluiddisplaced by said-pump;: a first electromagnet driving r said pumpga-first winding forming-part of said first electromagnet and energized" by an alternating current; a control member inserted betweensaid pump andsaidpiston so as to control the flow of 1 pressure fiuid; from said pump to' said piston; a second electromagnetdriving-said controlmemher; and a second winding forming part ,ofsaid second-electromagnet and energized by an alternating current-having the 'sameirequency as the alternating current energizing said first winding. 2-. An electrohydraulicmoving devicecomprising in combination, a piston adapted tobe con- "nected Ito a part'gto-"be moved; by the device; a pump operatively: connected; to: said, piston so as-to;displa'cetha sameby, a pressure fluid displaced by said pump; xazfirstelectromagnet driving said pump; a first winding :Iormingv part of said; first electromagnet and-venergized by an alternatingxcurrent;a5 control member. inserted between-saidpump and said piston so as; to :control the flow of'pressurefluid from saidpumpto said piston; a second electromagnet driving said control member and arsecondwindingt forming part of said second electromagnetand energized by'an alternatingicurrent having the'same frequency-as the alternating current energizing said first winding, the current energizing said second winding having a phase lag amounting to 45 as compared to the' current energizing {said first her; a second windingformingflpart of said sec- 0nd electromagnet and-energized by an alternating current having'thes'ame ierquency as the alternating current energizing said first winding;

means forshifting the phase of the alternat ing current energizing-said second winding against the phase of the alternating current-energizing said first winding whereby the pressure and quantity of the fluid displaced byj'the pumpcan be adjusted. v i v 4. An electrohydraulic moving device comprising in combination; 'a piston adapted tobe connected to a part to'be moved; by thedevice; a pump operatively connected to said piston so as to displace the'same by a pressure fluid displaced by said pump"; first electromagnet driving said pump; a, firstwinding forming part of said firstelectromagnet and'e'nergizedb'y an alternating current; 'a control'niember inserted .between said pump and saidjpistonjso as .to control the flow of pressure fluid fromjsaidpump to said piston; a second; electromagnet driving said control member; a second winding forming part of said secondelectromagnet and energized by an alternating current having the same frequency as the alternating current energizing saidfirst Winding; and means for inverting the phase of one of the-currents energizing isaid windings in order to reverse the directionof the displaceinents of the pressure .fluid. a V

5. An electrohydraulic moving device comprisingin combination, a; piston adapted to be connectedto a part to be moved-by the-device; a pumping system. operatively connected'to said piston so as to displace the same by a pressure fluid displaced by said pumpingsystem; a first electromagnet driving said pumping system; a first Windingforming part of said'electromagnet and energized by an alternating current having a predetermined frequency, said pumping system being tuned to the, frequency oithe alternating current energizing said first winding; a control member inserted between said pumping system and said pistonso as to controlthe flow of pressure, fluid from said pumping system to said piston; a second electromagnet driving said control member; and a second Winding formingrpart of said second electromagnet and energized by an alternating current having the'same frequency as the alternating current energizing said first winding.

6. An electrohydraulic movingdevice comprising. in combination,- a piston adaptedlto be connected to a part to be moved. by the device; a pump operatively connected to said piston so as to displace the same by a'pressure fluid displaced by'said pump; afirst electromagnet driving said pump; a first winding forming part of said first electromagnet and energized by an alternating current; a control member having controlfslots and being inserted between saidpump and said piston so as to control the'fiow ofpressure fiuid from said pump tov said piston; a second electromagnet driving said control rnember; and a second winding forming part of said second electromagnet and energized by an'alternating current having the same frequency as the alternating current energizing said first winding, said control member being tuned to resonance with the frequency of the alternating currents energizing said windings so that said control slots can be extended.

'7; An electrohydraulic moving device comprising in combination, a first piston adapted to be connected toa part to be moved by'thedevice; a pump operatively connected to said first piston; a second piston forming part of said pump and displacing, a pressure fluid acting on said first piston; a first electromagnet driving said pump;

a first winding forming part of said first electromagnet and energized by an alternatingcurrent; a control member arranged at right angles to said second piston and inserted between said pump and said piston so as to control the flow of pressure fluid from said pump to said piston; a'second electromagnet driving said control member; and

'a second winding forming part of said second electromagnet and energized by an alternating current having the same frequency as the alternating current energizing said first winding.v

8. Anelectrohydraulic moving device comprising in combination, a piston adapted to be connected to a part-to be moved by "the device; a pump operatively connected to said piston so as to displace the same by a pressure fluid displaced by said pump; a first electromagnet driving 'said pump; a first winding forming part. of said first electromagnet and energized by' an alternating current; a hollow controtmember inserted being in combination; a piston adapted to be con-.

tween said pump and'saidipiston' so as to control thefiowpf, pressure fluidxfrom said pu'mp to said.

piston ;i:a:fse,cond electromagnet driving said :con-

trlolmember; a secondwinding iormirig "part :of

saidsieconwelectromagnet an energized. byan alternatingcurrent having the same frequencyas Yi..:9;i An ielectrchydraulic fniovingi-device comprise ing in combination, aY Ypiston..adapted. to be connected; toYapart-. tojbe moved bythe ;device a pump.operativelyi-connected tosai piston so :as

pumptga ifirst minding; formingipart Yzof'qs'aidifirst ele trom gn t and ;e1.1ergized.. by: an alterna in current; YY;a hollcwiscontrol, member. inserted 1-be- Y tod'isplace. the same by. a pressure, fluid displaced byi said pump;faffirst-electromagnet zdrivingysaid twe said 'numoandsam Ypistoniso as toicontrol.

the-flow of pressure fluid from .isaid: pump tosaid piston; a second electromagnet driving said; control-member; a secondwinding forming partof said second electromagnet and energized by an alternating current havingthe same frequency, as.

the alternating current energizing said first winding; and resilient, means arranged, Within said hollow control member and rendering the same part of an oscillating; system having a predetermined natural frequency being in resonance with therrequency of the alternating currents energizing;said windings;- r; j. I. YY

An electrohydraulic movingdevicecomprisnected to a part to be moved the device; a

pump operatively connectedtosaid piston so as todisplace the same by;a,pressu-refluid displaced by said;; mp a'first electromagnet-driving said pumpqandhaving a first magnetiocoreand a first winding 5 arranged on :said first; core, said first winding being energized by an ualternating. currentat-a rating voltage, said firstgcore and said first'winding. being so dimensionedthat said first core. is saturated if a current atithe rating voltage flows, in said, first winding; a control member insertedbetweensaidpumpand said piston so as to control the flow of;pressure .fiuid from saidpump'to said piston; a second electromagnet driv-' ing said control member; and a second winding; 50

forming part of I said second electromagnetand energized by an alternating 'current having the same frequency as the alternating current energizingisaid' firstwindingh 1'1. An electrohydraulic moving device comprising in combination, a pi'stonadapted to'be connecte to a part to bemoved by the device; a pump operativelyconnected to'said piston so as to displace the same by a pressure fluid displaced by'said pump; a first electromagnet driving said pump; a first winding'forming' part of said first electromagnet and I energized by I an; alternating current; acontrol member inserted between said pump and said pistonfso asto contr ol' the flow of pressure fluid rromsaiapum to' said piston;

a second electromagnet driving said control member; and having a magnetic; core anda" second winding arranged on said coreysa'id secondwinding being energized by an alternatingcurrent at a rating voltage having the same frequ'ency as the alternating currentenergizing'said-first winding;

saidcore'and said second winding; being so dimen-,

sioned that said core is saturated if an alternating current at the Winding.

rating voltage flows in said "second '12. An electrohydraulic moving device comprising. incombination, a piston adapted; to be connected to a part to be moved by the device; a pump operatively connected to said piston 'so as to displace ;'the same by apres'sure flui .idisplac'ed by said; pump ya first electromagnet .drivin'g said pump andhaving a first magnetic core and a first winding arranged on said first core, said first winding: being energizediby an alternating current at a" rating voltage said "firsticore and said first winding being so dimensioned that said first core is saturated if .acurrent atithe rating voltage flowsin said first windingfa control member inserted between said .pump and saidpi'ston so as 130 00111'1101111116 flow: of pressure fluid .from said pumpto saidpistonya secondelectromagnet driving said control -member and having-a second magnetic core an a second winding arranged on said second core, said second winding. being energizedby anfalternatingcurrent at a rating voltage having the :same frequency as the alternating current energizing said firstwinding, said second core and said second :-winding being so dimensioned that saidsecond core is saturated if an alternating current at the-rating voltage flows in said second winding. Y Y Y Y 13. 'An electr'ohydraulic moving device comprising'incombination, a tank containing a pressure fluid a pump arranged within said tank and having a piston; I a first electromagnet Y arranged in said tank-and drivingsaid pump; a first winding forming part ofsaid first electromagnet and energized by analternating current; .a control member arranged in-said tank; Y a cylinder arranged in said tank; a piston arranged in said cylinder and adapted; to be connected to a, part to be movedbythe device, said control member being inserted between said pump and said cylinder'so as to control the flow of pressure fluid from said pump to said cylinder; ,a second elec trornagnet driving said control member; a second winding forming part of said second electromagnet and energized by an alternating current having the same frequency as the alternating current energizing said first winding; and means for securing said pump and said electromagnets to saidtank, said securing means damping any vibrations produced by said pump and being independent of said cylinder and said piston arranged in said cylinder. Y 1 Y '14. An electrohydraulic moving device comprising in combination, a tankcontaining a pressure fluid; a pump arranged within said tank and having a pistom-a first electromagnet arranged in saidtank and driving said pump; a first winding forming part of 'said first electromagnetand energized by an alternating current; a control memberarranged insaid tank; a cylinder'arranged ;in said tank; apiston arranged in said cylinder and adapted to be connected to a part to be moved by the device,- said control member being inserted between said pump and said cylin- 

